Energy efficient domestic refrigeration system

ABSTRACT

An energy transfer system (12) for a household refrigeration appliance (110). The energy transfer system (12) includes a venting system (120) within the refrigeration appliance (110), and a set of conduits (130,132) for enabling the transfer of outside air into, through and out of the venting system. The system (120) moves cooling air around the storage compartment (122,124) and compressor (162). In one form of the present invention, the system may also include a thermostatically actuated valve (38) for enabling outside air into, through and out of the compartment (114) in response to a predetermined temperature.

RELATED APPLICATIONS

This application is a continuation-in-part of Ser. No. 995,980, filedDec. 23, 1992, now U.S.Pat. No. 5,291,749 with the same title, thespecification and drawings of which are herein expressly incorporated byreference.

BACKGROUND OF THE INVENTION

The present invention generally relates to domestic refrigerators andfreezers. More particularly, the present invention relates to a systemand method for utilizing cool outdoor ambient temperature levels toreduce the energy required to operate a domestic refrigerator or freezersystem.

Virtually every home and apartment in this country has at least onerefrigerator for storing perishable food products. Additionally, manyhouseholds also have a freezer for storing food products over extendedperiods of time. As a consequence of such widespread usage, thesedomestic appliances consume a substantial part of the electrical energywhich is generated by the nation's utility companies. In this regard, itshould be noted that refrigerators are considered to be a relativelyinefficient appliance. Indeed, it has recently been reported that asidefrom electric heaters, refrigerators rank as the next most inefficientappliances in the home. Since even the newest refrigerators consumeapproximately 700 kwh of electricity per year, it should be understoodthat a substantial need still exists to increase the energy efficiencyof domestic refrigeration appliances.

Accordingly, it is a principal objective of the present invention toprovide a system and method which reduces the energy required to operatedomestic refrigerator and freezer systems.

It is another objective of the present invention to provide an energyefficient domestic refrigeration system which minimizes the heatgenerated inside a home when the outdoor ambient temperature exceeds adesired indoor temperature.

It is an additional objective of the present invention to provide adomestic refrigeration system which potentially reduces the quantity ofrefrigerant needed in the system.

SUMMARY OF THE INVENTION

To achieve the foregoing objectives, the present invention provides anenergy transfer system for a household refrigeration appliance. Theenergy transfer system includes a venting system within the refrigeratorhousing, and a set of conduits for enabling the transfer of outside airinto, through and out of the venting system. In one form of the presentinvention, the system may also include a thermostatically actuated valvefor enabling outside air into, through and out of the venting system inresponse to a predetermined temperature.

The set of conduits preferably includes a first conduit for enabling thetransfer of outside air to the venting system, and a second conduit forenabling the transfer of air from the venting system to the outsideenvironment. Each of these conduits are disposed such that they extendthrough an external wall of said household. To facilitate the convectionflow of air, the outlet of one conduit is connected to the compartmentat a location which is lower than an inlet connection of the otherconduit.

Additional features and advantages of the present invention will becomemore fully apparent from a reading of the detailed description of thepreferred embodiment and the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a household refrigeration appliance inaccordance with the present invention.

FIG. 2 is a side elevation view of the refrigerator shown in FIG. 1.

FIG. 3 is a schematic representation of a refrigeration system.

FIG. 4 is a graph of the vapor-compression refrigeration cycle for therefrigeration system of FIG. 3.

FIG. 5 is a perspective view of a refrigeration appliance in accordancewith the present invention.

FIG. 6 is a cross-sectional view of FIG. 5 along line 6--6 thereof.

FIG. 7 is a cross-sectional view of FIG. 5 along line 7--7 thereof.

FIG. 8 is a partial cross-sectional view of an alternative embodiment ofthe present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to FIG. 1, a perspective view of a household refrigerationappliance 10 in accordance with the present invention is shown. Morespecifically, the household refrigeration appliance depicted in FIG. 1is a domestic refrigerator which has been retro-fitted with the energytransfer system 12 in accordance with the present invention. However, itshould be understood that the principals of the present inventions areequally applicable to a domestic refrigerator which has been constructedat the originating factory to include a built-in energy transfer system.Additionally, it should be appreciated that the present invention isdirected at household refrigeration appliances, such as self-containedrefrigerators and freezers, that are specifically adapted for use in ahome environment. In this regard, it should be understood that acompletely different set of constraints and design criteria may beemployed with commercial refrigeration equipment, which have acompressor and refrigerator cabinet in separate locations.

As shown in FIG. 1, the refrigerator 10 generally includes at least onedoor 14 across its front and a serpentine tube condenser 16 mountedacross its back and bottom. As well known in the field, the condenser 16is connected to the discharge end of a pump to compress a refrigerantfluid, such as freon, from a gaseous phase to a liquid phase. Thisprocess creates heat which must be removed in order for therefrigeration cycle to work. In this regard, FIG. 3 shows a schematicdiagram of a conventional refrigeration cycle, with the pump indicatedby reference numeral 18. An expansion valve 20 is used to permit thecompressed refrigerant to expand in an evaporator coil 22, which isdisposed within the interior of the refrigerator 10. This process ofexpansion operates to remove heat from the interior of the refrigerator10.

With this household refrigerator arrangement, the heat produced at thecondenser 16 is simply released into the area of the home whichsurrounds the refrigerator. However, in accordance with the presentinvention, a compartment 24 is used to enclose the condenser 16. Asshown in FIG. 1, the compartment 24 may be comprised of a five-sidedmolded fiberglass shell which is mounted to the exterior side of therefrigerator 10 where the condenser 16 is located. In this regard, thecompartment 24 includes a flange 26 which extends around its peripheryin order to able the compartment to be secured to the refrigerator 10over the condenser 16, such as with a plurality of spaced screws.However, it should be understood that the compartment may be comprisedof other suitable materials and may take other suitable shapes in theappropriate application. For example, with a factory built-in energytransfer system, the compartment 24 may be formed integrally with a sideof the refrigerator 10, such that the consumer need not discern that thecompartment is included as part of the refrigerator body. Additionally,the compartment 24 may be constructed such that it includes aninsulative layer in order to more fully control the transfer of heatfrom the condenser 16.

The energy transfer system 12 also includes one or more passageways forenabling the transfer of heat out of the compartment 24 and forselectively utilizing outside air in this process. Thus, for example, asshown in FIGS. 1 and 2, the energy transfer system 12 includes a firstconduit 28 which enables cool air from outside of the home to enter thecompartment 24, and a second conduit 30 which enables air from insidethe compartment to be released outside of the home. In this regard, bothof these figures show an exterior wall 32 of the household wall, and theconduits 28 and 30 are constructed such that they are able to extendthrough this exterior wall. The conduits 28 and 30 may be made of anysuitable material which is appropriate for this purpose (e.g., sheetmetal or flexible insulated duct), and the conduits may be connected tothe compartment in a variety of ways.

It should also be noted that the first conduit 28 is connected to thecompartment 24 at a location which is lower than that where the secondconduit 30 is connected to the compartment. This arrangement is used tofacilitate outside air from through the first conduit 28 into thecompartment, through the compartment and out of the second conduit 30 byheat convection. While the conduits 28, 30 are shown to be relativelystraight pipes or tubes, it should be understood that other suitableshapes may be employed, depending upon such considerations as theavailable space and the distance between the refrigerator 10 and theexterior wall 32.

FIGS. 1 and 2 also show the provision of a fan 34, which may be used toforce the flow of outside air into, through and out of the compartment24. While the fan 34 is shown to be connected to the compartment 24 in away which is separate than the connection of the conduits 28, 30 to thecompartment, it is preferred that the fan be connected in-line with thefirst conduit 28, either within the conduit or adjacent to its outletinto the compartment. Additionally, it is preferred that the fan 34 be athermostatically actuated fan, so that the its use may be carefullycontrolled to achieve the most energy efficient benefit.

Additionally, as shown in FIGS. 1 and 2, the energy transfer system 12also includes a movable barrier or wall in one or both of the conduits28, 30 to control the flow of air through the compartment 24. In oneform of the present invention, this movable barrier is comprised of abutterfly valve 36 which may be used to prevent or enable the flow ofoutside air into the compartment via a butterfly valve disposed in oneor both of the conduits 28, 30. For example, in the case of butterflyvalve 36 disposed in the second conduit 30, the flow of outside airthrough the first conduit 28 could provide sufficient force to open thebutterfly valve, and thereby permit the escape of air from thecompartment 24 through the second conduit.

From the above, it should be understood that the energy transfer system12 conveys energy in the form of cool outside air to the condenser 16,in order to reduce the energy consumption of the refrigeration process.In other words, the present invention transfers available energy fromthe environment to the refrigeration cycle components, instead of havingto transfer some of these refrigeration cycle components outside to theenvironmental energy source. The introduction of available energy to therefrigeration cycle reduces the energy required from the cycle, andconsequently increases the overall energy efficiency of the refrigerator10. This increase in energy efficiency would also enable the use ofsmaller, more efficient refrigeration components and reduce the amountof refrigerant required for a new refrigerator unit.

The following analysis may be used to demonstrate the energy efficiencyimprovement by examining the increase in the refrigerator enthalpy "h".This analysis is set forth below in connection with the reference pointsshown in FIGS. 3 and 4.

Assume 1: In the evaporator the heat absorbed per unit mass=the changein enthalpy of the refrigerant.

Assume 2: At point 7 the refrigerator is a saturated liquid.

Assume 3: At point 8 the refrigerator is a saturated gas.

Assume 4: The refrigerator is freon 12.

Assume 5: Typically the temperature around the expansion valve is 40° C.and the temperature existing at the evaporator is -20° C.

Following all the assumptions the enthalpys are below:

h₅ at 40° C.=74.527 KJ/KG

h₅ at 10° C.=45.337 KJ/KG

h₈ at -20° C. 184.619 KJ/KG

P₈ is 150 KPa

h₈ -h₅ (40° C.) 110.092=X₁

h₈ -h₅ (10° C.) 139.282=X₂

Increase in heat per unit mass absorbed at a percentage ##EQU1##

In other words, assuming that the outside air temperature is low enoughsuch that the temperature at point 8 can be brought down to 10° C. froma level of 40° C., then a 20.96% increase in heat per unit mass absorbedmay be achieved.

Thus, in accordance with the present invention, the fan 34 may beactuated when the outside air temperature drops to a predeterminedthreshold level (e.g., 37° C.), as the energy efficiency achieved willbe greater than the energy consumed by the fan. Alternatively, it shouldbe appreciated that the refrigerator 10 may already include a fan whichmay be used to divert some air flow into the compartment 24 from theoutside. The energy transfer system 12 may also include athermostatically actuated valve, such as the valve which would enableambient air from inside the household (e.g., 20° C.) to enter the 9compartment 24 when the outside air temperature is above a particularthreshold level (e.g., 37° C.). In this way, the compartment 24 willalways be provided with a sufficient supply of air flow to cool thecondenser 16.

Turning to FIGS. 5 through 8, additional embodiments of the presentinvention will be described. FIG. 5 illustrates a refrigerator 110having a split door 112 and a housing 114. The housing 114 surrounds therefrigeration compartment 116 which includes freezer 122 and coldstorage 124 compartments. Also illustrated in phantom is a ventingsystem 120.

As seen in FIGS. 6 and 7, the freezer 122 and cold storage 124compartments are surrounded by insulation 126 to maintain apredetermined cold temperature in the compartments. The venting system120, as illustrated in FIGS. 5 through 7, may surround the compartments122, 124 or it may be strategically positioned at the top, sides, orbottom of the refrigerator housing. The venting system 120 may takevarious forms, however, it may be as simple as a gap between theinsulation and housing enabling circulation of cold air from the inlet130 around the compartments within the housing and exiting outlet 132.Various types of spacers or the like may be utilized to form the gapbetween the insulation and housing.

As illustrated, cold air enters the inlet 130, and is diffusedthroughout the top of the refrigerator. The air moves along the sidesaround the storage 122 and freezer 124 compartments. The cool air thenmoves around the compressor area 136 and the bottom of the compartmentsand exits out of the refrigerator. Various types of films or the likemay be utilized to cut down on dust and condensation, if present,between the housing and the insulation. As the air circulates within therefrigerator housing 114 and is directed toward the inlet, the hot airgenerated around the compressor is also collected and exited from therefrigerator. Thus, by providing cool air circulating around the storageand freezer compartments, it requires less work from the compressor,since the hot air surrounding the compartments has been removed. Thus,this increases the efficiency and decreases the amount of work performedby the compressor which, in turn, reduces the overall electricconsumption of the refrigerator.

In FIGS. 5 through 7, the air flow is shown entering the refrigeratorhousing through the inlet 130. As the air enters the inlet 130, it isdeflected by a number of channels 140 separated by vanes 142. As the airdeflects around the vanes into the channels, it is directed along thesides of the refrigerator, as seen in FIGS. 5 through 7. Upon flow alongthe sides of the compartment, the air is directed towards the compressorarea 160. The air circulates around the compressor 162 and then exitsthrough the outlet 132. A number of different vane and channel designsmay be utilized to move the air throughout the refrigerator. Thus, thespecific numbers of vanes and channels for movement of the air may bemodified as desired to optimize the cooling of the area. Also, anadditional conduit 170 and valving may be coupled with the inlet 130.The conduit 170 includes valves 172, 174, 176 which open and close todirect air flow into the refrigerator housing. In cases where theambient temperature is above a desired temperature where it will notcool the storage compartments but cool the compression area, the valves172, 174, 176 can be adjusted to direct the air flow directly into thedesired area.

FIG. 8 illustrates an additional embodiment of the present invention. InFIG. 8, the inlet 130 empties into a bag like membrane 150 positioned inthe gap between the housing and the insulation. The bag membrane 150enables the air to enter into the membrane and then pass along the topand sides of the refrigerator and then exit in the compressor area. Thebag membrane provides a dust barrier between the housing and theinsulation enabling the air to move alongside the storage and freezercompartments without creating an abnormal amount of dust. Also, themembrane would collect condensation, if any, and direct it out of thebag. Other types of barriers or venting systems may be utilized toprovide the necessary cooling between the compartments and the housing.

Preferably, the compressor cooling fan would be utilized to draw the airinto the housing. However, an additional fan may be used.

Also, as mentioned above, a thermostatically actuated valve, fan or thelike may be positioned into the conduits for enabling passage of air.Also, conduits would be adaptable to receive air from the ambientsurroundings of the refrigerator.

The present invention has been described in an illustrative manner. Inthis regard, it is evident that those skilled in the art once given thebenefit of the foregoing disclosure, may now make modifications to thespecific embodiments described herein without departing from the spiritof the present invention. Such modifications are to be considered withinthe scope of the present invention which is limited solely by the scopeand spirit of the appended claims.

What is claimed is:
 1. A refrigeration or freezer appliance comprising:ahousing surrounding at least one cooling storage compartment;refrigeration means for cooling said at least one cooling storagecompartment; and cooling means for adding and removing air between saidhousing and at least one cooling storage compartment, said cooling meanscoupled between said housing and at least one cooling storagecompartment and with an air source and said air added or removed by saidcooling means cooling said refrigeration means.
 2. The refrigerationappliance according to claim 1, wherein said cooling means furthercomprises an inlet and outlet for enabling ingress and egress of air anda venting system positioned within said housing for circulating the airthrough and out of said housing.
 3. The refrigeration applianceaccording to claim 2, wherein a gap is formed between said housing andat least one storage compartment.
 4. The refrigeration applianceaccording to claim 2, wherein said venting system includes one or moreair deflecting members.
 5. The refrigeration appliance according toclaim 2, wherein said inlet and outlet are coupled to the outsideenvironment.
 6. The refrigeration appliance according to claim 1,wherein said refrigeration means includes a fan means and said fan meansdrives air through said coupling means.
 7. The refrigeration applianceaccording to claim 6, wherein a valve means provides air flow for saidcooling means and said valve means opening and closing isthermostatically controlled.
 8. A method of reducing the energy requiredto operation a refrigeration or freezer appliance, comprising the stepsof:providing a refrigerator with a housing and at least one storagecompartment; coupling a cooling means between said housing and at leastone storage compartment; and causing outside air to flow into, throughand out of said cooling means and cooling a refrigeration means when theoutside temperature reaches a predetermined threshold.
 9. The methodaccording to claim 8, further comprising enabling the inside air to flowinto, through and out of said cooling means when the outside temperaturehas not reached said predetermined threshold.
 10. The method accordingto claim 8, wherein said step of causing outside air to flow includesthe step of forcing outside air to flow into, through and out of saidhousing.